Thesis (M. Med (Rad. Diagn.)) --University of Limpopo, Medunsa Campus, 2011 / Objective: The objective was to determine the incidence of missed pathology on normal non contrast enhanced cranial computed tomography (NECT).Method: Records of cranial computed tomography scans done over a 12 month period at the Dr George Mukhari Hospital were evaluated by three readers. The NECT and contrast enhanced cranial computed tomography (CECT) were read at separate occasions and readers did not have access to a history, each other’s interpretation or to their own interpretation of the NECT when the CECT was evaluated. The data was evaluated and analysed after the 3 readers had seen the cases individually. Interpretation discrepancies were resolved during a meeting between all 3 readers and consensus was reached. Cases with missed pathology on the NECT were evaluated retrospectively at a joint meeting between the 3 readers to determine whether the pathology was visible on the NECT and thus to determine the combined reader error rate. Results: In this study 3.28 % of cases had pathology missed by 3 readers on the NECT. Retrospective viewing reduced this to 1.42% indicating a reader error of 1.85%. This incidence of missed pathology correlates with the most recent studies done. Having a thorough medical history of the patient and selecting those with clinical findings indicating the need for a CECT will reduce the incidence of missed pathology.Conclusion: Patients with a normal NECT and no fever, meningism, confusion, focal/lateralizing signs, a history of tuberculosis or tumours, or risk factors for dural venous sinus thrombosis have a very small chance of missed pathology on NECT. The risk of contrast induced adverse events outweighs the risk of missing pathology on a normal NECT provided there is no clinical indication necessitating a CECT. Omitting unnecessary CECT will in turn reduce the risk of intravenous iodinated contrast and the radiation exposure to the patient. These two factors will ultimately reduce the running cost of the CT department and increase the throughput of patients. Alternatively omitting the NECT will reduce the radiation exposure to the patient.Reporting errors can be reduced by assessing and managing risk factors in each department i.e. viewing conditions and workload.

Cranial sutures are fibrous joints of the skull which allow for growth in young individuals. The sutural ligament is the fibrous connective material found between the two joint surfaces which can be divided into a number of different layers. During embryonic development and growth, ossification centres in the skull allow for the growth and development of the flat bones in the skull. Sutures are the areas where these ossification centres eventually meet. Some sutures like the frontal suture normally disappear at the age of two years, but it has been shown that this suture can persist in adulthood and is then called the metopic suture. Torgersen (1950) has shown that the obliteration pattern of the metopic suture is the same for skulls belonging to common inheritance trajectories. Cranial suture closure has thus been shown to be controlled by genes. In physical anthropology, obliteration of cranial sutures has been used as an age-at-death indicator since 1542. However, in 1890, Dwight rejected the notion that there was any relationship between age and obliteration patterns. Despite this, there have been a number of studies that have continued to use this method to estimate age-at-death from skeletal remains. These methods are currently still being used. The aim of this study was to investigate cranial suture obliteration patterns in adult crania. A total of 490 randomly selected modern black and white South African skulls from the Dart Collection were used to collect data. The ages of the individuals ranged from 19 to 98 years. Two methods previously used to estimate age from skeletal remains were used to assess the final obliteration status of the sutures. The scores assigned to these sutures were then subjected to statistical analyses to explore any relationship between age, sex and population affinity. The results show that considerable polymorphism in the obliteration pattern of the cranial vault sutures exist. The endocranial scores are bimodal while the ectocranial aspects using both the Acsádi & Nemeskéri (1970) and Meindl & Lovejoy (1985) method are multimodal. Bimodality and multimodality are direct indications of polymorphism. No significant relationship was found between obliteration and age. Thereafter the two methods initially used to assess the sutures were used to estimate the age of the skulls to test these methods. The results show that both these methods are not useful as age estimators when used on individuals drawn from the South African black and white populations. Since the large majority of variation in cranial suture obliteration is not explainable by age, it is hypothesized that patterns of the cranial vault suture obliteration are the result of epigenetic variation similar to that occurring elsewhere on the skeleton, and not a regular result of aging. / Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, 2009

Cranial sutures are fibrous joints of the skull which allow for growth in young individuals. The sutural ligament is the fibrous connective material found between the two joint surfaces which can be divided into a number of different layers. During embryonic development and growth, ossification centres in the skull allow for the growth and development of the flat bones in the skull. Sutures are the areas where these ossification centres eventually meet. Some sutures like the frontal suture normally disappear at the age of two years, but it has been shown that this suture can persist in adulthood and is then called the metopic suture. Torgersen (1950) has shown that the obliteration pattern of the metopic suture is the same for skulls belonging to common inheritance trajectories. Cranial suture closure has thus been shown to be controlled by genes. In physical anthropology, obliteration of cranial sutures has been used as an age-at-death indicator since 1542. However, in 1890, Dwight rejected the notion that there was any relationship between age and obliteration patterns. Despite this, there have been a number of studies that have continued to use this method to estimate age-at-death from skeletal remains. These methods are currently still being used. The aim of this study was to investigate cranial suture obliteration patterns in adult crania. A total of 490 randomly selected modern black and white South African skulls from the Dart Collection were used to collect data. The ages of the individuals ranged from 19 to 98 years. Two methods previously used to estimate age from skeletal remains were used to assess the final obliteration status of the sutures. The scores assigned to these sutures were then subjected to statistical analyses to explore any relationship between age, sex and population affinity. The results show that considerable polymorphism in the obliteration pattern of the cranial vault sutures exist. The endocranial scores are bimodal while the ectocranial aspects using both the Acsádi & Nemeskéri (1970) and Meindl & Lovejoy (1985) method are multimodal. Bimodality and multimodality are direct indications of polymorphism. No significant relationship was found between obliteration and age. Thereafter the two methods initially used to assess the sutures were used to estimate the age of the skulls to test these methods. The results show that both these methods are not useful as age estimators when used on individuals drawn from the South African black and white populations. Since the large majority of variation in cranial suture obliteration is not explainable by age, it is hypothesized that patterns of the cranial vault suture obliteration are the result of epigenetic variation similar to that occurring elsewhere on the skeleton, and not a regular result of aging. / Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, 2009

Thesis (M.S.)--University of Michigan, 2004. / Includes bibliographical references.

Forward genetic screens in the mouse are contributing significantly to our understanding of basic mammalian development and human disease. In one such screen, our laboratory has identified the novel mouse gumby mutant, which affects the development of the neural and vascular systems. Here, I describe the characterization of the gumby mutant phenotype and the identification of its causative mutation in a novel, vertebrate-specific gene, which is one of the genes deleted in patients affected by Cri du Chat Syndrome that exhibit mental retardation and craniofacial deficits. Expression and phenotypic analyses revealed a requirement for the gumby gene in the facial nerve axon guidance and angiogenesis. Lately, it has become evident that many common mechanisms and molecules operate during neural and vascular development. My results suggest that the gumby gene is an attractive candidate for regulating both processes and its analysis in the future may help us understand how the navigational mechanisms for both systems are intertwined. My studies show that gumby is a cytoplasmic protein that is present in many embryonic and adult tissues. In yeast-two-hybrid assays gumby interacts with a member of the highly conserved Wnt pathway - Dishevelled 2 (Dvl2). In both Dvl2-/- and gumby homozygotes, the level of the cardiac neural crest cell marker Plexin2A is decreased. The three branches of the Wnt pathway have been shown to regulate a wide range of events during embryogenesis and adult homeostasis, and subsequently have been implicated in multiple human pathologies. Taken together my data suggest that gumby may be required for Wnt signaling in angiogenesis and/or facial nerve guidance. Given that Wnt signaling has been shown to play key roles in axon guidance, gumby and its roles in Wnt signaling may also contribute to the mental retardation seen in patients with Cri du Chat Syndrome. Thus, further analyses of molecular and biologic roles of gumby will provide important avenues for understanding the cell biology of human disease.

No description available.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Thesis (Ph.D.) in Biochemistry and Molecular Biology--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 102-111).

Thesis (M.S.)--Ohio State University, 1975. / Bibliography: leaves 51-55. Available online via OhioLINK's ETD Center.

Thesis (M.S.)--Ohio State University, 1975. / Bibliography: leaves 36-39. Available online via OhioLINK's ETD Center.